1. Field of the Invention
The present invention relates to a display device and a driving method of the same, and more particularly, to a display device which includes poly silicon and a driving method of the same.
2. Description of the Related Art
Recently, flat panel display devices such as a liquid crystal display devices and organic light emitting diodes (OLEDs) have been replacing cathode ray tubes (CRTs) as they become more widely used.
An OLED includes an organic light emitting layer which receives an electron and a hole and emits light. The OLED has been popular since it is driven with a low voltage, is light and small, has a wide viewing angle, and has a fast response speed. Typically, an OLED includes a thin film transistor. The emission intensity of the organic light emitting layer is determined by the number of holes supplied from a pixel electrode that is connected with the thin film transistor.
A semiconductor layer that makes up a part of the thin film transistor may include amorphous silicon or poly silicon crystallized with amorphous silicon. If the thin film transistor includes poly silicon, mobility is excellent and thus a driving circuit may be embedded in a substrate. Also, a large-scale integration is available, and an aperture ratio is improved since the thin film transistor is designed with a smaller size.
The semiconductor layer affects the quality of the thin film transistor, which in turn affects the display quality of the OLED. If a voltage is supplied without consideration of the property of the semiconductor layer, the OLED may not properly express gradations.